Evaluation of the preoperative staging of rectal cancer by MRI

Objective To evaluate the value of pelvic MRI in the preoperative staging of rectal cancer. Methods Fifty patients suspicious of having rectal cancer underwent pelvic MRI scans after cleansing enema. Forty-seven of 50 patients were proved to have rectal cancer by colonoscopy and/or pathological examination. The MRI findings of 40 patients underwent surgical intervention were compared with the pathological examination for staging. Results The diagnostic accuracy rate of rectal cancer was 95.7% (45/47) by MRI. The overall accuracy rate of T-staging was 82.5% (33/40) by MRI, including T1-2-staging 69.2% (9/13), T3-staging 90.0% (18/20) and T4-staging 85.7% (6/7). The accuracy rate for serosal infiltration was 92.6% (25/27), and 63.2% (12/19) for lymph node involvement. Conclusion Pelvic MRI showed high accuracy for the diagnosis and preoperative staging of rectal cancer, and was useful to detect the serosal infiltration and lymph node metastasis.